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Database scaling & optimization

Indexing, connection pooling, read replicas, query tuning, and throughput-aware SQL.

6 matches

Composite index leftmost prefix in Python

Simulate a composite index in SQLite and check whether query columns match the leftmost prefix rule for index usage.

import sqlite3


def get_indexed_columns(table_name):
    """Simulate a composite index by reading column names that start with 'idx_'."""
    conn = sqlite3.connect(":memory:")
    conn.execute(f"CREATE TABLE {table_name} (id INTEGER, idx_col1 TEXT, idx_col2 INTEGER, other TEXT)")
    conn.execute(f"CREATE INDEX idx_…

13 0 Open

Database scaling & optimization medium

Cross Shard Query Scatter Gather Mock in Python

Simulate a distributed database cross-shard query using a scatter-gather pattern with a mock Python implementation.

scatter-gather sharding distributed-systems

Python

from dataclasses import dataclass
from typing import List, Dict


@dataclass
class NodeResponse:
    node_id: int
    data: Dict[str, float]


def mock_query_shard(shard_id: int, shard_data: Dict[str, float], query: str) -> NodeResponse:
    """Simulate querying a single shard, returning matches whose value > 50."""
 …

13 0 Open

Database scaling & optimization easy

Database indexing and query timing optimization in Python

Create SQLite indexes and time query performance to measure speedup for large table lookups in Python.

sqlite indexing query optimization

Python

import sqlite3
import time


def time_query(db_path, query, params=()):
    conn = sqlite3.connect(db_path)
    conn.execute("PRAGMA journal_mode = WAL")
    start = time.perf_counter()
    result = conn.execute(query, params).fetchall()
    elapsed = time.perf_counter() - start
    conn.close()
    return result, ela…

14 0 Open

Database scaling & optimization medium

How to Create a Covering Index with INCLUDE Columns in Python

Create a covering index with INCLUDE columns in SQLite from Python and inspect the query plan to confirm the index covers the query.

sqlite indexing covering index

Python

import sqlite3

def create_covering_index_mock():
    conn = sqlite3.connect(":memory:")
    cursor = conn.cursor()

    cursor.execute("""
        CREATE TABLE employees (
            id INTEGER PRIMARY KEY,
            name TEXT,
            department TEXT,
            salary INTEGER
        )
    """)

    employe…

15 0 Open

Database scaling & optimization medium

How to Eager Load with JOIN to Reduce N+1 Queries in Python

Demonstrates eager loading with a SQL JOIN to reduce N+1 query patterns down to a single database call when fetching related data.

eager-loading n-plus-1 join

Python

import sqlite3


def eager_load_join_reduce(mock_db_path=":memory:"):
    """Demonstrate eager loading where joins reduce query count from N+1 to 1."""
    conn = sqlite3.connect(mock_db_path)
    cursor = conn.cursor()
    cursor.executescript(
        """
        CREATE TABLE authors (id INTEGER PRIMARY KEY, name TE…

16 0 Open

Database scaling & optimization medium

How to Explain SQLite Query Plans in Python

Build a Python function that runs EXPLAIN QUERY PLAN on SQLite in-memory tables and prints the optimizer's execution plan for any SELECT statement.

sqlite query-plan optimization

Python

import sqlite3

def explain_query(sql: str) -> str:
    """Return the SQLite query plan for the given SQL statement."""
    conn = sqlite3.connect(":memory:")
    cursor = conn.cursor()
    
    # Create sample data for a realistic plan
    cursor.execute("CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)")
    c…

14 0 Open

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